Stephen d



(Model.)

S. D. FIELD. Underground Telegraph.

Patented Oct. 19, 1880.

INETOR 7) @4 2%/ WITNES BY g ATTORNEYS.

N. PETERS, PHOTO L THOGRAFHER UNITED STATES PATENT EEICE.

STEPHEN D. FIELD, OF NEW YORK, N. Y.

UNDERGROUND TELEGRAPH.

SPECIFICATION forming part of Letters Patent No. 233,492, dated October 19, 1880.

Application filed March 13, 1880. (Model.)

To all whom it may concern:

Be it known that I, STEPHEN D. FIELD, ot' the city, county, and State of New York, have invented a new and useful Improvement in Underground-Telegraph Lilies, of which the following is a specification.

The object of my invention is to prevent the accumulation of and to remove. moisture from underground tubes containing telegraph-wires, and thereby insure the insulation of the wires; and my invention consists iu the combination, with a system of underground tubes, of mechanical means for maintaining a circulation of dry air and drying or condensing chambers for relieving the air of moisture.

In the accompanyingdrawings, forming part of this specilication, Figure l is a sectional elevation of my underground-telegraph line constructed in accordance with my invention, and Fig. 2 is a transverse section.

Similar letters of reference indicate corresponding parts.

A A are sealed tubes containing the insulated wires a.. These tubes are laid in pairs in a trench, or within an outer pipe, as shown in Fig. 2. At one end the tubes A are connected together by a tube, b, and at the other end the tubes A aijconnected to a drying or condensing chaml er, B, and a pump or airforcing apparatus, C. The chamber C contains chloride cfcalcium or other material having affinity for moisture. The pump C is fitted with an inlet-valve in its connection to the chamber B and an outlet-valve in its connection to tube A, so that by operation of the pump the air shall be drawn from one tube A through the chamber B, and discharged into the other tube A, a continual circulation being thereby kept up through the tubes. The air,

as it passes through the chamber B,is relieved of its moisture, and the dry air forced into the tubes will take up any moisture there may be in the tubes.

By these means the difficulties heretofore experienced from moisture in underground tubes containing telegraplrwires are prevented.

The pumps and drying-chambers are to be located at the extremities of the pipe system, or at several points in the line, as may be required.

In place of the chamber containing chemi cals, as described, a refri geratin g-cha-m ber ma y be used for producing condensation by cold.

In some cases the drying or condensing chamber may be dispensed with and a circulation ot' air through the sealed pipes depended on for carrying olf the moisture.

I am aware that artificially-dried air has been used to till underground-telegraph tubes, and also that reservoirs of material having ainity for moisture have been placed along' the line of pipe; but no means have been used for bringing the imprisoned air continuously in contact with the drying agent.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- The sealed pipes A A, connected at one end by a tube, b, and at the other communicating respectively with a drying-chamber, B, and airpump C, said pump and drying-chamber being themselves connected, as shown and described.

STEPHEN D. FIELD.

Witnesses:

GEO. D. WALKER., O. SEDGWIOK. 

